Method and device for exposing a substrate to light

ABSTRACT

The invention concerns a method for exposing a substrate ( 1 ) equipped with an n-layer photoresist system ( 2 ), an electrically conductive connection being created between a ground potential and the substrate ( 1 ) and/or at least one of the layers S 1  through S n  of the photoresist system ( 2 ). The invention furthermore concerns an arrangement for carrying out said method. According to the present invention, what is achieved in a single process step is that by way of spring elements E 1  through E 4 , a contact tip K 1  is advanced as far as the layer S 1 , a contact tip K 2  is advanced through the layer S 1  as far as the layer S 2 , a contact tip K 3  is advanced through the layer S 1  and S 2  as far as the layer S 3 , and so forth. The electrical charges from the layer S 1  are dissipated to the ground potential via the contact tip K 1 , the charges from the layer S 2  via the contact tip K 2 , etc., and/or and from the substrate ( 1 ) via a contact tip K 4 .

CROSS REFERENCE TO RELATED APPLICATIONS

This invention claims priority of a German filed patent applicationDE-A-198 53 093.5.

FIELD OF THE INVENTION

The invention refers to a method for exposing a substrate, equipped withan n-layer photoresist system, with a corpuscular radiation, anelectrically conductive connection being created between a groundpotential and the substrate and/or at least one of the layers S₁ throughS_(n) of the photoresist system in order to dissipate electricalcharges. The invention further refers to an arrangement for carrying outthis method.

BACKGROUND OF THE INVENTION

Methods and arrangements for patterning substrates, for example masks orwafers, in which the substrate is coated with a photoresist and thatphotoresist layer is exposed to a corpuscular radiation, for example anelectron radiation, in order to impress the predefined pattern upon thesubstrate, are known. For exposure, the substrates are placed onto thesupport surface of a stage movable in the X and Y coordinates andretained there while the stage is moved step by step in the X and/or Ydirection and thereby brought at successive points in time intopredefined exposure positions in which the corpuscular radiation isdirected at right angles, corresponding to the Z coordinate, onto thephotoresist layer.

The photoresist is made of an electrically nonconductive material thatbecomes electrostatically charged during irradiation. The substrate canalso become electrostatically charged. This side effect, referred togenerally as “charging,” can unintentionally result, especially in thecase of photoresist layer material thicknesses>1 μm, in an influence onthe radiation direction of the corpuscular radiation and thus inexposure errors and pattern defects, thus defeating efforts in themicroelectronics industry toward increasingly finer patterns. To remedythis, a variety of methods and arrangements for dissipating electricalcharges out of the photoresist layer and/or out of the substrate duringexposure have been developed.

JP Patent 60-117720, for example, describes an electron beam exposuremethod in which the electrical charge is dissipated from a specimenequipped with a nitride or oxide layer by the fact that a needle made ofa very hard, initially electrically nonconductive material, such asdiamond, sapphire, or the like, is made conductive by the implantationof, for example, boron ions and is then used to penetrate through thelayer until contact is made with the specimen. This results in groundingof the specimen via the grounded needle, and thus causes dissipation ofthe charge that has accumulated in the specimen during exposure. Becauseof the hardness of the material, the needle has a long service life,although relatively large forces must act on the needle in order topenetrate the nitride or oxide layer.

In this context, the advance movement of the needle is limited by thespecimen material, i.e. the specimen constitutes the stop for the needleand prevents it from pushing forward into the specimen material beyond adesired degree. Disadvantageously, this method and the arrangementdepicted in this context are suitable only for contacting a specimenconcealed beneath a layer, by penetration through that layer. If,however, what is provided as the specimen is a substrate onto which aphotoresist system made up of several layers has been applied, and ifeach of the layers is to be individually contacted and connected to aground potential by way of a separate needle, this procedure isunsuitable, since the needles are always pushed through the entire layerstructure until contact is made with the substrate.

A further JP Patent 3-263814 assumes that it is known, for example inthe case of a mask board that is equipped with a chromium layer and aphotoresist located above the chromium layer, to penetrate through thephotoresist layer with the tip of a contact pin, to create anelectrically conductive connection to the chromium layer lyingtherebeneath, and thereby to dissipate the undesired electrons out ofthe chromium layer through the pin to a ground potential. According tothe patent, this method is improved in that the contact pin, uponpenetration through the photoresist layer and while contact is made withthe chromium layer lying therebeneath, is caused to rotate about itslongitudinal axis in order to achieve reliable contact and at the sametime to increase the service life of the tip of the contact pin, sincethe pin can now be of rounded configuration. Leaving aside the increasedequipment complexity involved in a rotational drive for the pin, hereagain the disadvantage exists that contacting of each individual one ofa plurality of layers of a photoresist system cannot be performed inthis fashion.

JP Patent 2-125416 describes an arrangement for creating an electricalcontact between a cassette (ground potential) and a chromium layer thatis located on a mask baseplate beneath a photoresist. In this, outsidethe area that is reserved on the mask of the patterning, a pin is pushedby way of a leaf spring onto the surface of the (electricallynonconductive) photoresist layer. The tip of an electrode that isconnected to a high-voltage source is then pushed through thephotoresist, in the vicinity of said pin, as far as the chromium layer,and then a voltage of a few hundred to ten thousand volts is applied tothe electrode; the photoresist thereby experiences an insulationbreakdown as a result of which the pin resting on the photoresist isconductively connected to the chromium layer, and dissipation of chargesoccurs to the cassette via the pin and the leaf spring.

This technical solution is also not suitable, nor is it provided, forcontacting each individual one of a plurality of layers of a photoresistsystem.

SUMMARY OF THE INVENTION

Proceeding from this existing art, it is the object of the invention todevelop a method of the kind described above in such a way that in thecase of a substrate equipped with a multi-layer photoresist system,before exposure begins each individual one of the layers S₁ throughS_(n) of the photoresist system, and if necessary also the substrateitself, is brought into electrically conductive connection with a groundpotential.

According to the present invention, the object is achieved in that in aprocess step before exposure begins, the substrate and/or the layers S₁through S_(n) are brought into electrically conductive connection withthe ground potential by way of a quantity of m contact tips K₁ throughK_(m), by the fact that the coated substrate and the contact tips K₁through K_(m) are moved relative to one another until the electricallyconductive connection between the ground potential and the substrateand/or each individual layer S₁ through S_(n) is created by way of atleast one of the contact tips K₁ through K_(m) in each case.

This uncomplicated process step advantageously ensures that there iscreated, between the ground potential and each individual one of thelayers S₁ through S_(n) and the substrate, an ohmic contact by way ofwhich the electrical charges occurring during exposure are effectivelydissipated. Any undesired influence on the radiation direction caused byelectrical charges is thus prevented, and an essential prerequisite foraccurate exposure and for a further refinement in patterns is thuscreated. The disadvantages of the existing art described above are thuseliminated.

According to the invention, what is achieved in a single process step isthat, for example, a contact tip K₁ is advanced until contact is madewith the layer S₁, a contact tip K₂ is advanced through the layer S₁until contact is made with the layer S₂, a contact tip K₃ is advancedthrough the layers S₁ and S₂ until contact is made with the layer S₃,and so forth, and lastly a contact tip K_(m) is advanced through thelayers S₁ through S_(n) until contact is made with the substrate. Theelectrical charges from the layer S₁ are dissipated to the groundpotential via the contact tip K₁, the electrical charges from the layerS₂ via the contact tip K₂, from the layer S₃ via the contact tip K₃, andfrom the substrate via the contact tip K_(m).

This procedure at the same time has another advantageous effect, namelythat the contact tips K₂ through K_(m) dissipate not only the chargesfrom the layers S₁ through S_(m) to which they have been advanced, butalso those from the layers S₁ through S_(m−)that they have penetrated.For example, the contact tip K₂ dissipates not only the electricalcharges from the layer S₂, but also, because of the ohmic contactcreated during penetration, those from the layer S₁. The same isanalogously true of the contact tip K₃ with respect to the layers S₁ andS_(2,), and so forth.

In a variant embodiment of the invention, provision can be made for onlythe layers S₁ through S_(n) of the photoresist system to be connected toground potential, in the manner described, each via a contact tip K₁through K_(n). In this case the number of contact tips is equal to thenumber of layers.

As an alternative to this, however, it is conceivable for the number ofcontact tips to be greater than the number of layers. It is thenpossible to allocate to the individual layers S₁ through S_(n) and/or tothe substrate not just one but a plurality of contact tips, and thus toincrease the reliability with which electrical charge is dissipated fromdefined layers or from the substrate. In this context, contact toselected layers and to the substrate can be made with the aid of aplurality of contact tips that are arranged at different positions onthe periphery of the wafer or mask. This is advisable in particular ifthe layers S₁ through S_(n) are segmented, and the individual segmentsare not electrically interconnected. For example, one contact tip can beassigned to each segment of such a layer.

It is moreover possible in this manner to allocate to each individuallayer S₁ through S_(n) and to the substrate, depending on the specificconductivity of the layer material, a number of contact tips whichreliably guarantees rapid dissipation of resulting charges from allregions of that layer.

According to the present invention, the manner in which the contact tipsare advanced relative to the coated substrate is such that the materialof the particular layer to be penetrated by a contact tip is eitherdisplaced or removed.

Displacement of the material upon penetration of a layer is attained bythe fact that the contact tip, acted upon by a predefined advance force,is guided on a straight motion path, preferably in the Z direction,through that layer. Because of the wedge effect upon penetration of thecontact tip into the particular layer and upon further insertion, thelayer material is displaced sideways in the X, Y direction.

As an alternative to this, however, a particularly preferred variantembodiment of the invention provides for the advance movement of thecontact tips to take place substantially in the Z direction, but for theadvance movement to have superimposed on it a component in the directionof coordinate X and/or Y. This laterally directed motion componentcreates a “scratch effect” as the contact tips penetrate, as a result ofwhich the layer materials are removed by the contact tips in locallylimited fashion, and intimate contact is thus made with the exposedlayer.

The invention furthermore refers to an apparatus for patterning asubstrate that is equipped with a plurality of layers S₁ through S_(n)forming a photoresist system, in which a corpuscular radiation isdirected onto the photoresist system for the purpose of exposure, andmeans are provided for dissipating to a ground potential the electricalcharges that form during exposure in the photoresist system.

According to the present invention, in an apparatus of this kind atleast a number of contact tips corresponding to the number n of layersS₁ through S_(n) is provided, of which one contact tip is assigned toeach of the layers S₁ through S_(n) and each of the contact tips isconnected to the ground potential via an electrical conductor. Inaddition, the coated substrate and the contact tips are arranged movablyrelative to one another in the direction of the corpuscular radiation.

In a preferred variant embodiment, the coated substrate is placed on asupport plane that is movable in the direction of the corpuscularradiation as far as a position Z₁, while each of the contact tips ismechanically joined to a frame-mounted holding fixture via a separatespring element. Each contact tip is thus movable, in response to a forceallocated to it and predefined by the spring element, relative to theother contact tips and also relative to the frame-mounted holdingfixture.

This individual mounting of the contact tips on separate spring elementsas defined by the present invention makes it possible to assign to eachcontact, by corresponding design of its spring element, a specific forcewith which that contact tip acts on the photoresist system when thesubstrate is shifted into the position Z₁.

Provision is also made, according to the present invention, for theindividual contact tips to be configured with different geometries interms of their tip angle α and tip radius R. It is thus possible, basedon known relationships between force and area and in consideration ofthe thickness and viscosity of the layer materials, to coordinate thespring elements and tip geometries of the contact tips with one anotherand with the layer materials in such a way that a predefined penetrationdepth into the photoresist system is achieved when the substrate isshifted into the position Z₁.

For example, the tip angle α and tip radius R of a contact tip K₁ andthe force F₁ allocated to it by the spring element E₁ are to becoordinated, with one another and in terms of the thickness andviscosity of a layer S₁, in such a way that when the support plane forthe substrate is moved to the position Z₁, the contact tip K₁ cannotpenetrate through the layer S₁ but rather simply rests on the layer S₁,and the electrically conductive connection between the layer S₁ and theground potential connected to the contact tip K₁ is created.

Provision is also made, for example, for the geometry of a contact tipK₂ and the force F₂ to be coordinated, with one another and in terms ofthe thickness and viscosity of the layer S₁, in such a way that when thesubstrate is moved into the position Z₁, the layer S₁ is penetrated bythe contact tip K₂ and the contact tip K₂ rests on the layer S₂, so thatthe electrically conductive connection between the layer S₂ and theground potential is created via the contact tip K₂. Analogously, thegeometry of the contact tip K₃ and force F₃ are coordinated, with oneanother and in terms of the thickness and viscosity of the layers S₁ andS₂, in such a way that when the substrate is moved to the position Z₁,the layers S₁ and S₂ are penetrated by the contact tip K₃ and theelectrically conductive connection between the layer S₃ and the groundpotential is created via the contact tip K₃.

This applies in the same fashion to the further contact tips; ultimatelyat least the geometry of the contact tip K_(n) and force F_(n) arecoordinated, with one another and in terms of the thickness andviscosity of the layers S₁ through S_(n−), in such a way that when thesubstrate is moved to the position Z₁, the layers S₁ through S_(n−)arepenetrated by the contact tip K_(n) and the electrically conductiveconnection between the layer S_(n) and the ground potential is ensuredvia the contact tip K_(n).

The method and the arrangement according to the present invention arepreferably applicable in conjunction with a substrate that is equippedwith a photoresist system made up of three layers S₁ through S₃, thelayer S₁ comprising a polymer photoresist, preferably of the designationPMMA, the layer S₂ comprising silicon nitride, and the layer S₃ onceagain comprising PMMA.

In this context, a very advantageous variant embodiment of the apparatusaccording to the present invention consists in the fact that four springelements E₁, E₂ . . . E₄, configured as leaf springs, are present, eachof which is joined immovably at one end to the holding fixture while theallocated contact tip K₁, K₂ . . . K₄ is attached at the respectiveother end. These leaf springs can have imparted to them, as a functionof the layer materials and by way of varying configuration of the springmaterial, spring cross section, and spring length, the properties that,upon movement of the substrate into the position Z₁, produce springforces F₁, F₂ . . . F₄ which ensure that the contact tip K₁ reaches itsallocated layer S₁, the contact tip K₂ its allocated layer S₂, thecontact tip K₃ its allocated layer S₃, and the contact tip K₄ thesubstrate.

The forces are to be set in a range from 0.1 N to 2 N, and the tip radiiof the contact tips are to be embodied in the range from 20 μm to 100μm, while the thicknesses of the layers are between 0.5 μm and 2 μm.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention is described with reference to theembodiments shown in the drawings.

FIG. 1 shows a coated substrate before contacting;

FIG. 2 shows the coated substrate in the contacted state;

FIG. 3 shows a plan view of the substrate and contact tips;

FIG. 4 shows the substrate and contact tips in a side view in directionA of FIG. 3;

FIG. 5 shows the movement path of a contact tip during contacting; and

FIG. 6 shows an example of the geometry of a contact tip in detail.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a portion of an apparatus for patterning a substrate 1 thatis equipped with a photoresist system 2. For purposes of patterning byway of a corpuscular radiation that is directed onto photoresist system2 in direction 3 parallel to coordinate Z, the coated substrate 1 isplaced on support plane 4 of a stage 5.

Photoresist system 2 comprises layers S₁ through S₃, the layer materialprovided for the layer S₁ being PMMA, for the layer S₂ silicon nitride,and for the layer S₃ once again PMMA.

Before exposure begins, substrate 1 is first positioned relative to anexposure optical system (not depicted in the drawing) by the fact thatstage 5 along with substrate 1 is moved in coordinate Z out of aposition Z₀ until a predefined distance between surface 6 of photoresistsystem 2 and the exposure optical system has been established. Let it beassumed that, for example, that distance is achieved at position Z₁(FIG. 2). After this movement, stage 5 with substrate 1 can be moved insteps in the direction of coordinates X and/or Y into the individualexposure positions.

In order to prevent charging effects that can undesirably influence thedirection of the exposure radiation, provision is made according to thepresent invention for each of layers S₁ through S₃ and substrate 1 to beconnected, even before the exposure begins, to a ground potential towhich the charge carriers can discharge without impediment. Thisconnection is achieved by the fact that the shifting movement of stage 5into position Z₁ is used to connect each individual one of layers S₁through S₃, and substrate 1, to the ground potential.

For this purpose, there are provided above photoresist system 1 in thedirection of coordinate Z, on a frame-mounted holding fixture 7, fourcontact tips K₁ through K₄, each of which is arranged on one of springelements E₁ through E₄ which are configured as leaf springs. Of the fourcontact tips K₁ through K₄, contact tip K₁ arranged on spring element E₁is associated with the layer S₁, contact tip K₂ arranged on springelement E₂ with the layer S₂, contact tip K₃ arranged on spring elementE₃ with the layer S₃, and lastly contact tip K₄ arranged on springelement E₄ with substrate 1 (FIGS. 3, 4).

For the sake of clarity, this arrangement is depicted in FIG. 1 and FIG.2 only with reference to spring element E₃ and contact tip K₃. It isevident here that spring element E₃ is attached at one end to a holdingfixture 7, while contact tip K₃ is located in freely oscillating fashionat the other end. Holding fixture 7 is immovably joined to a deviceframe 11.

When stage 5 is then shifted in direction Z, surface 6 reaches contacttip K₃, which thus first comes to rest on surface 6, but as the shiftingmovement proceeds is pushed ahead of surface 6. The preload on springelement E₃, and thus also the surface pressure between the mutuallycontacting surface segments of contact surface 8 and surface 6, therebyincreases. When the surface pressure becomes sufficiently great as theshifting movement proceeds, this causes the destruction of surface 6,and contact tip K₃ penetrates into the layer S₁. In this context, thepenetration depth depends on the geometry of contact tip K₃, inparticular on its tip angle α and tip radius R (cf. FIG. 6), and on theproperties of spring element E₃ and the viscosity of the layer S₁.

With a suitable coordination of the tip angle α, tip radius R, andspring element E₃ in terms of the viscosity and thickness of the layerS₁, contact tip K₃ passes through the layer S₁ and penetrates into thelayer S₂. Here again, the penetration depth into the layer S₂ depends onthe increase in force resulting from the rising spring preload orsurface pressure as the shifting movement proceeds. The result of therising surface pressure, again as a function of the consistency and ofcourse also the thickness of layers S₁ and S₂, is that the layer S₂ isalso penetrated and contact surface 8 comes into contact with thematerial of the layer S₃.

If the tip angle α, tip radius R, spring element E₃, and viscosity andthickness of layers S₁ and S₂ are coordinated with one another withsufficient accuracy, an electrical contact is thus made to the layer S₃,via contact tip K₃, spring element E₃, and an electrically conductiveconnection 9 to the ground potential, exactly when position Z₁ isreached.

This situation is depicted in FIG. 2, from which it is evident thatcontact surface 8 of contact tip K₃ has penetrated into photoresistsystem 2 as far as the layer S₃. Not only has the electricallyconductive connection been created between the layer S₃ and the groundpotential, but also, because of the contact between contact surface 8and the material of layers S₁ and S₂, these two layers have also beenconnected to the ground potential. When the exposure process thenbegins, electrical charges that form in undesired fashion are dissipatedto the ground potential.

FIG. 3 shows, in a plan view looking in direction 3, contact tips K₁through K₄ that are mechanically joined via spring elements E₁ throughE₄ to holding fixture 7. In this context, contact-tips K₁ through K₄ aremovable relative to one another, the movement direction correspondingapproximately to the perpendicular to the drawing plane.

FIG. 4 shows spring elements E₁ through E₄ with contact tips K₁ throughK₄ in a view in direction A of FIG. 3. It is evident here that contacttip K₁ is allocated to the layer S₁, contact tip K₂ to the layer S₂,contact tip K₃ to the layer S₃, and contact tip K₄ to substrate 1.

This allocation defines the fact that one of contact tips K₁ through K₃is responsible in each case for electrical contacting to one of layersS₁ through S₃, and contact tip K₄ for electrical contacting to substrate1. In this context, spring elements E₁ through E₄ and the geometries ofcontact tips K₁ through K₄ are to be coordinated with the thicknessesand viscosity of layers S₁ through S₃ in such a way that the surfacepressures generated during the shifting movement of stage 5 aresufficient to allow each of contact tips K₁ through K₃ to come intocontact with its respectively allocated layer S₁ through S₃, and contacttip K₄ with substrate 1.

The advantageous result of this is that without additional mechanicaldevices (in the form of rotational drives for the pins) or electricalcontrivances (e.g. high voltage applied to the photoresist system), areliable electrical connection from each of layers S₁ through S₃ andsubstrate 1 to the ground potential is ensured by way of the shiftingmovement alone.

FIG. 5 shows the movement path of a contact tip K₃ during contacting.Since each spring element E₁ through E₄ is immovably clamped in at oneend, contact tips K₁ through K₄ move, as stage 5 is shifted, along acircular arc 10 whose radius is determined by the respective springlength. Since stage 5 is guided in linear fashion, however, the positionof the respective contact points between contact tips K₁ through K₄ andcoated substrate 1 changes in the direction of coordinates X and Y.

In this context, FIG. 5a) shows, for example, position X₁ of the contactpoint between contact tip K₃ and surface 6 shortly before initialcontact. During penetration as shifting proceeds, however, the contactpoint moves increasingly toward position X₂ (cf. FIG. 5b)).

The result of this relative motion between contact tip K₃ andphotoresist system 2 is that contact tip K₃ does not penetrate throughlayers S₁ and S₂ in a straight line corresponding to the shiftingmovement, but rather that a “scratch effect,” so to speak, is producedduring penetration; this is essentially important for making reliablecontact. As a result, the material of layers S₁ and S₂ that are to bepenetrated is not merely displaced, but is removed, so that an ohmiccontact is reliably brought into being. In the process, layer materialfrom the penetrated layers S₁ and S₂ also slides onto contact surface 8.The same is analogously true of the other three contact tips K₁, K₂, andK₄.

FIG. 6 depicts the geometry of contact tip K₃, which here has, by way ofexample, a tip radius R=20 μm and a tip angle α=30°. Taking intoconsideration the aforesaid material of layers S₁ and S₂ and layerthicknesses of 1 μm, with a correspondingly configured spring elementE₃, this yields a downforce of contact surface 8 onto the layer materialon the order of 0.1 to 2 N, which is sufficient to allow contact tip K₃to penetrate through layers S₁ and S₂ to the layer S₃ during theshifting movement.

In alternative variant embodiments of the invention, it is of coursepossible to make the radius of circular arc 10 so large that (remainingwith the example of contact tip K₃) penetration of the initial layers S₁and S₂ takes place predominantly by material displacement. If the springlength of spring element E₃ is sufficient, the movement component X uponpenetration of contact tip K₃ into photoresist system 2 is then so smallthat the scratch effect is absent and thus no material removal, and onlymaterial displacement, occurs. Linear guidance of contact tips K₁through K₄ parallel to direction 3 is also conceivable, in which caseone or more of the spring elements can be configured as helical springs.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

PARTS LIST

1 Substrate

2 Photoresist system

3 Direction of corpuscular radiation

4 Support plane

5 Stage

6 Surface of photoresist system

7 Holding fixture

8 Contact surface

9 Conductor

10 Circular arc

11 Device frame

S₁-S₃ Layers

K₁-K₄ Contact tips

E₁-E₄ Spring elements

What is claimed is:
 1. A method for exposing a substrate, equipped withan n-layer photoresist system, with a corpuscular radiation, anelectrically conductive connection being created between a groundpotential and the substrate and/or at least one of the layers S₁ throughS_(n) of the photoresist system in order to dissipate electricalcharges, wherein in a process step before exposure begins, the layers S₁through S_(n) are brought into electrically conductive connection withthe ground potential by way of a quantity of m contact tips K₁ throughK_(m), by the fact that the coated substrate and the contact tips K₁through K_(m) are moved relative to one another until the electricallyconductive connection between the ground potential and each individuallayer S₁ through S_(n) is created by way of at least one of the contacttips K₁ through K_(m) in each case.
 2. The method as defined in claim 1,wherein in addition an electrically conductive connection is createdbetween the ground potential and the substrate via at least one of thecontact tips K₁ through K_(m).
 3. The method as defined in claim 1,wherein a contact tip K₁ is advanced until contact is made with thelayer S₁, a contact tip K₂ is advanced through the layer S₁ untilcontact is made with the layer S₂, a contact tip K₃ is advanced throughthe layers S₁ and S₂ until contact is made with the layer S₃, and soforth.
 4. The method as defined in claim 2, wherein a contact tip K₁ isadvanced until contact is made with the layer S₁, a contact tip K₂ isadvanced through the layer S₁ until contact is made with the layer S₂, acontact tip K₃ is advanced through the layers S₁ and S₂ until contact ismade with the layer S₃, and lastly a contact tip K_(m) is advancedthrough the layers S₁ through S_(n) until contact is made with thesubstrate.
 5. The method as defined in claim 1, wherein individual onesof the layers S₁ through S_(n) and/or the substrate 1 are brought intoconnection with the ground potential via further contact tips K₁ throughK_(m) whose quantity corresponds to the difference m−n.
 6. The method asdefined in claim 1, wherein the advance movement of the contact tips K₁through K_(m) is accomplished at least almost parallel to the directionof the corpuscular radiation, the material of the respective layers S₁through S_(n) to be penetrated being displaced until each of the contacttips K₁ through K_(m) has reached the layer S₁ through S_(n), or thesubstrate, allocated to it.
 7. The method as defined in claim 1, whereinthe advance movements of the individual contact tips K₁ through K_(m)have movement components in the X and/or Y coordinates, as a result ofwhich the material of the respective layers S₁ through S_(n) to bepenetrated is removed until each of the contact tips K₁ through K_(m)has reached the layer S₁ through S_(n), or the substrate, associatedwith it.
 8. An apparatus for patterning a substrate that includes aplurality of layers S₁ through S_(n) of a photoresist system, in which acorpuscular radiation is directed onto the photoresist system for anexposure, comprising: a plurality of contact tips K₁ through K_(m) fordissipating to a ground potential the electrical charges that formduring exposure in the photoresist system, wherein at least one of mcontact tips K₁ through K_(m) is allocated to each of the layers S₁through S_(n); each contact tip K₁ through K_(m) is connected to theground potential via an electrically conductive connection; and thecoated substrate and the contact tips K₁ through K_(m) are arrangedmovably relative to one another in the direction of the corpuscularradiation.
 9. The apparatus as defined in claim 8, wherein at least oneof the contact tips K₁ through K_(m) is allocated to the substrate. 10.The apparatus as defined in claim 8, wherein the coated substrate isarranged on a support plane that is movable in the direction of thecorpuscular radiation as far as a position Z₁, while the contact tips K₁through K_(m) are separately joined mechanically to a frame-mountedholding fixture via spring elements E₁ through E_(m), each of thecontact tips K₁ through K_(m) being movable, in response to a force F₁through F_(m) allocated to it and predefined by the spring elements E₁through E_(m), relative to one another and relative to the holdingfixture.
 11. The apparatus as defined in claim 10, wherein the geometryof the contact tip K₁ and the force F₁ defined by the spring element E₁are coordinated, with one another and in terms of the thickness andviscosity of the layer S₁, in such a way that when the substrate ismoved to the position Z₁, the electrically conductive connection betweenthe contact tip K₁ and the ground potential is created.
 12. Theapparatus as defined in claim 8, wherein the geometry of the contact tipK₂ and a force F₂ are coordinated, with one another and in terms of thethickness and viscosity of the layer S₁, in such a way that when thesubstrate is moved into the position Z₁, the layer S₁ is penetrated bythe contact tip K₂ and the electrically conductive connection betweenthe layer S₂ and the ground potential is created via the contact tip K₂;the geometry of the contact tip K₃ and a force F₃ are coordinated, withone another and in terms of the thickness and viscosity of the layers S₁and S₂, in such a way that when the substrate is moved to the positionZ₁, the layers S₁ and S₂ are penetrated by the contact tip K₃ and theelectrically conductive connection between the layer S₃ and the groundpotential is created via the contact tip K₃; and the geometry of acontact tip K_(n) and a force F_(n) are coordinated, with one anotherand in terms of the thickness and viscosity of the layers S₁ throughS_(n−1), in such a way that when the substrate is moved to the positionZ₁, the layers S₁ through S_(n−1)are penetrated by the contact tip K_(n)and the electrically conductive connection between the layer S_(n) andthe ground potential is ensured via the contact tip K_(n).
 13. Theapparatus as defined in claim 8, wherein the photoresist systemcomprises three layers S₁ through S₃, the layer S₁ comprising a polymerphotoresist of the designation PMMA, the layer S₂ comprising siliconnitride, and the layer S₃ comprising the polymer photoresist.
 14. Theapparatus as defined in claim 13, wherein four spring elements E₁through E₄, configured as leaf springs, are provided, each of which isjoined immovably at one end to the holding fixture and at the oppositeend to the allocated contact tip K₁ through K₄.
 15. The apparatus asdefined in claim 14, wherein the forces F₁ through F₄ of the springelements E₁ through E₄ lie in the range from 0.1 N to 2 N, the contactsurfaces of the contact tips K₁ through K₄ are equipped with radii R inthe range from 20 μm to 100 μm, and the thicknesses of the layers S₁through S₃ are approximately 0.5 μm to 2 μm.